Calves from cows fed canola grew more

A two-year study found that beef cows fed a high-fat diet containing canola seed produced heavier calves right from birth to slaughter.

John McKinnon, professor emeritus at the University of Saskatchewan, said he was surprised at the results of the study comparing a typical diet with one supplemented by canola and another with flax.

“I really was literally shocked to see the response in terms of body weight improvement in these animals,” he said at the Saskatchewan Beef Industry Conference.

The study included 75 Angus beef cows.

The control group was fed a typical diet of 35 percent grass hay, 37 percent barley straw and 28 percent barley grain containing about 1.4 percent fat.

A pellet replaced the barley grain in each of the other two groups.

The canola group received a pellet containing 15 percent canola seed, and the “flax” group was fed 15 percent flax seed. That added about 3.3 percent fat content.

McKinnon said the goal was to add about 300 grams of fat per day through the supplementation.

The canola contained about 59 percent monounsaturated fatty acids, while the flax was 64 percent polyunsaturated fatty acid.

“They’re basically the same energy content, the same amount of fat, but they differ in the nature of the fat,” he said.

The treatments were fed over the second and third trimesters.

McKinnon said the effects of the diets were first obvious on the dams.

Twenty-three days before calving, the cows on the control diet were significantly heavier than the others but their calves were born three kilograms lighter.

“The low fat cows are heavier (so) they are putting more energy into fat and less into the calf,” McKinnon said.

After calving, all the calves were managed the same. They were backgrounded on 50 percent silage and 50 percent concentrate and then finished on about 90 percent concentrate and 10 percent silage.

The study found that at weaning the calves from the cows fed the canola supplement were 10 kilograms heavier than the calves from the control and the flax diet.

As 300-day yearlings, the differences were more obvious.

“We now see that those canola calves are now 22 kg heavier than the low-fat and flax is now heavier than the control,” McKinnon said.

In particular, the male calves from the canola trial were significantly larger, he said.

At slaughter, the canola calves were 36 kg heavier even though they were all eating the same diet since birth. They were also 17 kg heavier than those fed flax, and those fed flax were 17 kg heavier than the control.

McKinnon qualified the results by noting that the heavier calves were probably also eating more.

The research also looked at the cost of feeding the diets. McKinnon estimated the cost of the control diet was about $1.70 per head per day, while the canola was $2.14 and the flax $2.43.

“Over the 180 days it was $71 more for the canola cows and $117 more for the flax cows,” he said.

The heavier calf carcasses returned $126 more than the control and $60 more than the flax.

“When you look at the increase in revenue over the increase in feed cost, the flax calves didn’t return that feed cost, whereas there was still $52 benefit to the canola calves,” McKinnon said.

He suggested there is more research opportunity to find out if these results are repeatable.

“I have a hard time explaining (the results),” he said.

“Why did these animals perform better on this canola pellet?”

However, he also said the study indicates that nutritional strategies for the cow can influence the post-natal growth of the calf.

If he were to repeat the study, he said he would likely look more closely at canola oil and seed rather than flax and whether the nature of the fat is a factor.

Other questions include whether the fat supplementation needs to be 180 days or if more strategic supplementation produces the same results. That could keep feeding cost down.

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